Browsing by Author "Murphy, Richard P."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Cure monitoring of a UV cured epoxy resin using a long period grating Mach- Zehnder interferometer
    (International Society for Optical Engineering; 1999, 2007-12-31T00:00:00Z) Buggy, Stephen J.; Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P.; Cutolo, A.; Culshaw, B.; Lpez-Higuera, J. M.
    A cascaded long period grating Mach-Zehnder interferometer is used to monitor the change in refractive index of a UV cured epoxy resin over a cure cycle. Fourier techniques are used to calculate the phase shift and frequency spectral amplitude of the associated fringe pattern during the cure. The results are compared with the refractive index change during cure calculated using a Fresnel reflection based technique.
  • Thumbnail Image
    ItemOpen Access
    Multiplexing of Fibre optic long period Grating based interferometric sensors
    (IEEE Institute of Electrical and Electronics, 2007-03-01T00:00:00Z) Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P.
    Two long-period gratings (LPGs) fabricated in series in an optical fiber form a Mach-Zehnder interferometer, producing a sinusoidal channelled spectrum within the characteristic LPG attenuation bands, which has the appearance of an interference fringe pattern. The phase of the fringes is sensitive to changes in the surrounding environmental parameters, such as refractive index. Fabrication of a number of identical cascaded LPG pairs with different separations produces independent fringe patterns of different frequencies within the attenuation bands. The application of basic Fourier techniques to analyze the transmission spectrum allows the phase of each fringe pattern to be determined independently, facilitating the differentiation of external effects acting on each interferometer
  • Thumbnail Image
    ItemOpen Access
    Nested long period grating interferometers
    (International Society for Optical Engineering; 1999, 2007-12-31T00:00:00Z) Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P.; Antonello, Cutolo; Brian, Culshaw; Jos, Miguel Lpez-Higuera
    The concept of nested fibre optic long period grating (LPG) based interferometers is introduced. A number of in-series, identical LPGs may be used to form a set of nested, multiplexed Mach-Zehnder interferometers that may demodulated and demultiplexed by virtue of a Fourier analysis of the optical spectrum. The concept is demonstrated by the use of three LPGs to form a nested set of interferometers.